1) Needs instructions. WASD + Space is alright as a control scheme but not universal. Also, you have to avoid enemies, not jump on them
2. Some thing is wrong with the hurtboxes. The spikes seems to have an invisible block around them that kills you. I couldn't get past level 6 because of it. I had to play level 3 a couple of times over because the spike elevator kept killing me. They also hurt you if you touch them on the sides. Rusty killed me a couple of times too when he first appeared.
Level 6 is missing the key counter.
The game is a cute and mostly functional but there's not much more to say about it.